DE1477708A1 - Machining rotary drill - Google Patents

Description

A 14765 April 10, 1963

SANDVIKENS JERNVERKS AKTIEBOLAG, Sandviken / Sweden

Machining rotary drill

The invention relates to a machining rotary drill with at least two cutting edges, which are arranged in angular directions spaced from one another around the drilling axis.

It is already known in rotary drills, a single cutting insert with a main cutting edge that extending from the periphery to the drilling axis, and providing a central minor cutting edge passing through the drilling axis passes through. The position of the cutting edges leads to an eccentric side force, which has the consequence that the Drill a strong pressure on the inside of the borehole

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ches exerts, whereby the walls of the borehole are deformed. It is also known to have two symmetrical main cutting edges and to provide a secondary cutting edge in the middle, but the chip flow is then often so large and the chips are so wide that their removal, especially with tubular drilling tools, is a problem will. The invention solves this problem by using shorter cutting edges and by having these be arranged at a distance from one another around the circumference so that the chip evacuation is facilitated, and at the same time the resulting side force is proportionate becomes small. Another advantage of the invention is that the regrinding of the drill in comparison to the previously known drills is facilitated in which the cutting edges in separate adjacent stages are subdivided.

The aim aimed at with the invention is achieved in that the cutting edges in different Directions produce only part of the surface of rotation that forms the base of the borehole. In its In its simplest form, this drill has only two main cutting edges, which are preferably diametrically opposite one another

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and possibly also a minor cutting edge in the middle. The sons each cover a zone of the surface of rotation in the catfish, so that together they produce the whole surface of rotation. There may be three or more cutting edges than the mi tt strength Sohneide be provided which ent in two oppositely situated groups are arranged such that the gaps between the zones, which are in the generated by the Sohneiden a group by the cutting in the other group can be edited. Sometimes a separate central cutting edge is not required, but this is usually desirable in order to achieve adequate cutting ability in the center. The invention is also applicable to core drills, in which case, of course, no central cutting edge is used.

The main feature of the invention is that each cutting edge produces only a limited zone of the total surface produced by the drill and that the adjacent zones are produced by cutting edges which are arranged in different angular directions.

The invention is described in more detail below in conjunction with the accompanying drawings, and

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although show:

Fig. 1 is a side view of an inventive Drill;

FIG. 2 is an end view of that shown in FIG Drill;

Fig. 3 is a view of the cutting insert in

Section along line 3 - J in FIG. 2 and on a larger scale;

Figure 4 is an end view of another embodiment of the drill bit of the present invention with four cutting inserts;

Figure 5 is an end view of another embodiment the drill with three cutting inserts;

Figure 6 is an end view of also another embodiment of the drill with four Cutting inserts;

7 shows a view of a further embodiment of the drill in longitudinal section;

W Fig. 8 is a side view of the in Fig. 7 Darge

set drill;

Figure 9 is an end view of the drill shown in Figure 7;

Fig. 10 is a side view, on an enlarged scale, of one of the cutting inserts of the drill shown in Fig. J;

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Pig. 11 a view in section along the line 11-11 in FIG. 10.

The drill shown in Fig. 1 has a sleeve part 10, which is driven to rotate with a Drill pipe can be connected. If necessary, the drill can be stationary and instead the workpiece can be turn. The sleeve part 10 is hollow so that the chips can be carried away along its inside. At the front part of the drill there are two cutting inserts 11 and 12, which are preferably made of cemented carbide, z. B. made of cemented carbide or cemented oxides. Guide strips or ribs are used to guide the drill 13 * 14 and 15 are provided, which are also preferably made of Cemented carbide are made. The insert 11 has a cutting edge 16 extending from the circumference of the drill extends at a distance d from the center and ends at a distance e from the center. ^

The insert 12 has a cutting edge I7, which does not extend to the circumference and its outer end is at a distance g, while its inner End is a distance f from the center. The distance e is equal to or slightly smaller than the distance g, so

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the cutting zone of the cutting edge I7 is a continuation of the The cutting zone of the cutting edge 16 forms, possibly with a slight overlap between the two zones, to ensure that a continuous surface is created. The cutting edges 16 and 17 are the main cutting edges. The center of the borehole is cut by the central minor cutting edge 18, which is at the center line 19 ends or cuts through this at a distance h. The cutting edges 16 and I7 are inclined and along the same conical surface of revolution is shown, while the cutting edge 18 in an opposite direction is inclined. In general, the cutting edges 16 and 17 are intended to be arranged along a contiguous surface be, but it is also possible that the cutting edge 17 is somewhat in front of the cutting edge 16, so that the generated Area is divided into two stages. It is not necessary that the cutting edges be straight through the center line 19 are directed, but they can be with reference to a plane through the cutting which the axis I9 contains, be directed obliquely. The cutting edges 16 and I7 can also be perpendicular to the drilling axis I9, but should the cutting edge 18 is preferably directed backwards towards the center be to get the best possible cutting ability in the

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Middle to ensure.

FIG. 3 shows, on an enlarged scale, a view of the central cutting edge in section along line 3 in FIG. 2. The other cutting edges can have the same cross section. The cutting insert 12 is provided on its front surface 31 with a recess 32 which is provided along the cutting edge 18. This recess has the task of deflecting and breaking the chips. The recess has a rake face 33 with a rounded part 35 on its lower part. Behind the cutting edge there is a free surface y \ which is inclined backwards with respect to the drilling direction.

It has been found to be important that the central cutting edge 18 extends to the drilling axis 19 by a to achieve effective and thorough cutting in the center of the borehole. To ensure this can the cutting edge 18 pass through the drilling axis and extend beyond this at a distance h, as already described and shown in FIG. When the insert is reground, the surfaces become 3 ^ and 35 with respect to the drilling direction backwards

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grinded in such a way that the edge still cuts through the axis I9 passes through.

The surface should be along the central cutting edge 18 33 in general.parallel to the drilling direction and contain the axis 19, however, the recess J2 be replaced by chamfering along the dashed line. The surface J1 should be parallel to the axis and are in front of the axle, as shown in Fig. 3, to enable the cutting edge to be removed after regrinding of the insert is held in place by the axis.

The front surface must be along the cutting edges 16 and I7 31 of the insert does not necessarily have to be parallel to the drilling direction, as this is not an essential condition is that the cutting edges are directed through the axis. The front surface 3I can then be inclined and one Form a negative or positive rake angle.

The end face of the drill is provided with openings 40 and 41 through which the clasp along the Inside of the drill can be led away. the

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However, the invention is not limited to tubular drills, but can also be applied to twist drills, in which case the chips along a spiral groove on the outside of the drill.

As mentioned, the usual shape of the surface created by the main cutting edges is conical and is also the shape of the surface Λ created by the minor cutting edge

preferably conical. Furthermore, the surface generated can be curved, flat, broken or discontinuous. The invention can be used for drilling a full bore, in which case the central cutting edge of course is necessary, however the invention is also applicable to drill bits for core drilling, in which case the Center cutting edge must be omitted. When core drilling, it is generally advantageous to use a secondary cutting edge use that of the cutting edge 18 similar and backwards is inclined towards the center in order to achieve a suitable deflection of the chips. The main cutting edges can be used with core drills perpendicular to the axis or directed backwards and outwards in the same way as with solid drills be.

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The guide ribs or strips 13 * 14 and 15 and the end face 42 of the insert 11 support the drill in the lateral direction. It is important, that the length of the cutting edges on both sides of the middle is about the same, so that the resulting side force Becomes zero or as small as possible. In the embodiment shown, the cutting edges are located in two directions from the center, however, they can, at least for large drills, in three or more directions spaced from the center.

Fig. 4 shows a drill with four inserts 50, 51 s 52 and 53 · The space 54 between the inserts 50 and 51 and the gap 55 between the insert 51 and the center can be two zones uncut, but these zones by the inserts 53 and 52 cut. The insert 52 is provided with a secondary cutting edge similar to the cutting edge 18. In the same way, the inserts 50 and 51 intersect longitudinal zones that are not cut in the space 56 between the inserts 52 and 53 and in the space 57 between the insert 53 and the periphery. To ensure a complete cutting

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To ensure that, the adjacent cutting zones can overlap slightly, as above described.

Pig. Fig. 5 shows a drilling tool with three cutting edges 60, 61 and 62, which are made in the same way as previously described, intersect adjacent rotation zones of the total surface produced.

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Figure 6 shows a drilling tool with four inserts, two of which extend to the periphery. In this case, the cutting zone of the insert 70 falls fully within the cutting zone of the insert 73. In the same way as described above, the rotating zone of the gap 74 is machined by the insert 73, while the gap J6 is machined by the insert 71 and the Space 75 through insert 72. f

The cutting edges in one direction from the center can be on the same insert plate or provided on separate plates sdn. If separate inserts are used for each cutting edge,

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this has the advantage that different carbide qualities correspond to the different cutting speeds of the inserts can be used. At the soldered connections, the narrower the connection is, also has lower internal stresses. On the other hand, it can sometimes be useful for other reasons be to provide the cutting edges on the same insert, resulting in a rigid design and easy insertion which enables stakes. In Pig. 7 to 9 is a tubular drilling tool 80 with two insert plates 81 and 82 shown. The plate 81 has two main cutting edges 84 and 83, which are separated from one another by a groove 86 in the insert, and a minor cutting edge 85. The Plate 82 is also provided with two cutting edges 87 and 88, which are separated from one another by a groove 89. The radial distance c of the groove 86 is smaller than the radial distance m of the groove 89, so that the zone of rotation of the Groove 86 is machined by the cutting edge 88 and the zone of rotation of the groove 89 by the cutting edge 83. The grooves have the task of dividing the chips.

In Fig. 10 the insert 81 is shown separately and in Pig. 11 in section along line 11 - 11 in Pig. 10.

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The drilling tool shown in Figs. 7 to 9 can also be modified and the same can be used Inserts for a twist drill can be used instead of the tubular drilling tool shown. The spaces in between between the main cutting edges, even if the inserts for two cutting edges are common, as in Fig. shown, be larger than shown in the drawing. The size of the gaps is determined in terms of drilling conditions chosen so that a suitable chip flow is achieved.

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Claims (9)

_ 14 claims 1. Machining rotary drill with at least two main cutting edges around the drilling axis in angular directions spaced from one another are arranged, characterized in that each main cutting edge only a limited zone of the by the drilling tool generated total area and that the zones adjacent to these zones through those main intersections are generated, which are arranged in other angular directions. 2. Drill according to claim 1, characterized in that the adjacent zones intersect one another. J. Drill according to the preceding claims, characterized by a central minor cutting edge that extends to and intersects the drilling axis and further is inclined to the drilling axis. 4. Drill according to claim 5, characterized in that that the central cutting edge is parallel to the drilling axis 909830/0028 BATH ORIGINAL U77708 - Has 15 le rake face. 5. Drill according to the preceding claims, characterized in that the main cutting edges in to the center are arranged diametrically opposite directions. 6. Drill according to the preceding claims, characterized in that different cutting edges, which are arranged in the same angular direction are located on the same insert. 7- hole according to the preceding claims with at least two main cutting edges in the same angular direction, characterized in that the zone of rotation of the space between the inserts by a Insert is processed, which is arranged in a different Winkelrich device. 8. Drill according to the preceding claims with a secondary cutting edge in the middle, characterized in that that the secondary cutting edge is on the same 9 0 9 8 3 0/0028 BAD ORiGHAL set as at least one of the main cutting edges is located, 909830/0028 Blank page